In recent years, waste pulp incineration has become a problem due to the large amount of carbon dioxide emissions. The effect of ammonium dihydrogen phosphate (ADP) as an additive agent was investigated by pyrolyzing ADP-supplemented pulp, and the yields of carbon fixation, phosphorus recovery, and nitrogen recovery were calculated. An ADP/pulp ratio of 0.01 mol/g was found to be the optimal amount of ADP addition according to the pyrolysis profile, N fixation, carbon yield, and surface properties. The addition of ADP significantly increased the carbon fixation yield from approximately 30 % to over 80 %. The product activated carbon with ADP possessed surface area of 730 m2/g, which was a 2.4-fold increase compared to 300 m2/g without ADP. In addition, the effect of ADP on intramolecular dehydration of pulp was quantitatively discussed by identifying the amount of water, which was about three water molecules from a 2-unit repetition of pulp structure.